The present invention is directed to a transport container made of corrosion-resistant steel for retaining very pure liquid chemicals. The container has top wall with at least one screw closure and an immersion tube having a connection piece extending to the bottom of the container. A protective collar, provided with openings, surrounds the screw closure in spaced relation thereto.
In the production of electronic components, such as integrated circuits, liquid chemicals are needed, the purity of which must be as high as possible. During transport, storage and handling, contamination of these chemicals must be avoided. Since, in many cases, these chemicals are toxic or harmful in other ways, an unintended overflow caused, for example by damaging the transport container, must be precluded with great certainty.
The requirement of excluding all contaminations is admittedly fulfilled by glass containers. However, danger of breakage precludes their use as transport containers. In order to keep the mechanical stresses low, synthetic resin containers used for these purposes have hitherto been exclusively made as pressureless containers. However, this makes it necessary also to carry out the removal of the chemicals without the use of pressure, namely by means of suction pumps. In that suction pumps have moving parts rubbing against one another, contamination by wear occurring in the pump cannot be completely excluded.
Transport containers made of steel of the initially mentioned type can admittedly be made as pressure containers for higher mechanical stressing; however, the immersion tube necessary for the removal gives rise to constructional difficulties. The immersion tube is usually a component of a removal fitting which is placed on the screw closure or closure flange of the container. Since the immersion tube extends freely into the container, it is subject to comparatively high mechanical bending stresses when the liquid contained in the container moves about during transport. Since the immersion tube must extend to immediately above the bottom of the container in order to make possible the greatest emptying, the danger exists that the immersion tube touches the bottom of the container, which can result in rubbing between the immersion tube and the bottom of the container. The resulting wear contaminates the liquid.